Monday, 15 February 2016

Research recently published in the Journal of Applied Ecology
shows that the shrinking of mudflats along the coasts of the Chinese Yellow Sea
is an increasing problem for migratory birds that travel between Siberia and
Australia.This research, led by
Theunis Piersma, shows that three wader species, the Knot, Great Knot and
Bar-tailed Godwit, are in decline because of one common factor: loss of food
and habitat along the coasts of the Yellow Sea.During our work at Chongming Dongtan we have been privileged to work not
only with David Melville, but also Professor Ma of Fudan University, two
members of the research team.

Chongming Island, at the mouth of the Yangstze is a remarkable place for
waders.However, we have witnessed the
remarkable speed of the loss of intertidal areas along the coast through
reclamation, and also the threats, such as wind farms and shell-fisheries on
the remaining areas. The photographs here show some of the research, the threats and the diversity of waders that occur on this coast.

Wednesday, 3 February 2016

Chongming Dongtan is
one of the most important wintering sites in China for Hooded Cranes, with the
majority of the population wintering in Japan at one site, Izumi.It is a threatened and declining species with
a global population of around 11,000 birds.At
Chongming Dongtan, it winters primarily on the saltmarsh.Sea Bulrush Scirpus
mariqueter is a dominant species in the saltmarsh vegetation; and its
corms and seeds forma major food source for
the cranes (and other wintering waterbirds such as Tundra Swan).One study showed that the corms and rhizomes composed
about 99% of the total food content of the
cranes.

The corms in the outer saltmarsh
zone (far from the seawall) are easier to find by the cranes as they are buriedunderground shallower than those in the inner zone due to daily erosion
by tidewater. So, for easy access to food, Hooded Crane tended to select
the regions near the channels at low tide as their foraging habitat. Despite the similar food content between Hooded Crane and Tundra Swan, obvious
ecological separation occurs in their
foraging behaviour, foraging times and foraging habitats.

However, the
native Scirpusmariqueter dominated tidal vegetation is highly threatened and
diminishing rapidly.Land reclamation
is a major threat all along the Chinese coast but the native vegetation is also
being out-competed by the non-native Smooth Cord-grass Spartina alterniflora(the
eradication of which is the focus of our project at Chongming). Human activities such as fishing, and notably eel
fishing at Chongming Dongtan, have resulted in serious disturbance to the Hooded Crane and other
waterbirds.Although the cranes continue
to focus their activity on the remaining good quality saltmarsh, they now also increasingly
feed in rice paddies just over the sea wall, particularly at high tide.One of the reserve projects at Chongming is
to create ‘sacrificial’ rice paddies in safe locations for the benefit of the
cranes and other waterbirds.

We found a mixed flock of 70 Hooded and 18 Common Cranes loafing and
displaying on the upper areas of the saltmarsh.Interestingly, there was one family of apparent hybrid Hooded x Common
Cranes, a not infrequent occurrence.These birds displayed the bulk and general colour of the Commons but had
a washed-out Hooded head pattern.

Pics- above: Hooded Cranes (with Common Crane in the background).

Below: cranes on the salt marsh with distant fishing boats and bouys, displaying Hooded and Common Cranes with some hybrids in the foreground.

A grizzled old ecologist/birder, usually to be found roaming around the Lee Valley and occasionally further afield. Fortunate to be involved in the management of some of the UK's finest nature reserves and always looking for ways of improving them for birds.